1. Field of the Invention
The present invention relates to a motion guide apparatus, such as a ball screw device, and more particularly to a motion guide apparatus or ball screw device including a number of ball or roller bearing members disposed or attached or mounted or engaged between two movable members, such as an elongated bolt or screw shaft and a ball nut member, and a lubricating device for supplying or applying or distributing the lubricating grease or oil into the helical threaded portions or grooves of the movable members and for suitably lubricating the ball or roller bearing members.
2. Description of the Prior Art
Various kinds of typical motion guide apparatuses, such as the linear motion guide apparatuses or the ball screw devices have been developed and comprise two movable members rotatable or movable relative to each other, and a number of ball or roller bearing elements disposed between the two movable members for facilitating the sliding movement between the two movable members.
For example, U.S. Pat. No. 3,885,842 to Furutsu, U.S. Pat. No. 3,940,191 to Tomioka et al., U.S. Pat. No. 6,152,606 to Shirosaki et al., and U.S. Pat. No. 7,220,059 to Gobel et al. disclose several of the typical motion guide apparatuses or ball screw devices each comprising a ball nut pivotally or rotatably coupled onto a screw shaft, and a number of loaded ball bearing elements disposed between the screw shaft and the ball nut for facilitating the sliding movement between the screw shaft and the ball nut, and each further comprising an outer bearing ring and an inner bearing ring and a number of tapered rollers which roll between the bearing rings in two rows next to one another on the raceways of the bearing rings and kept apart at uniform distances by a respective bearing cage.
With the fitting of the bearing in machines or the like, the individual rings are usually positioned relative to one another by an interference fit on a shaft in such a way that production-related tolerances during the production of the individual parts of the antifriction bearing are compensated for, and defined axial prestress is produced between the tapered rollers of both rows. This axial prestress enables the bearing to roll free of play to the greatest possible extent under load.
The measures for defining the degree of the axial prestressing of the individual rings of an axially split bearing ring relative to one another, which measures were known up to the time of the prior patents and are still customary today, were in this case either to grind down the end faces of the touching end faces of the individual rings in an appropriately dimensionally accurate manner or to grind down in a dimensionally accurate manner the end faces of a separate distance ring arranged between the individual rings and then to join together all the individual parts in an accurately fitting manner.
A conceivable improvement of this state would therefore be to already connect together the individual rings of the axially split bearing at the bearing manufacture by means of clamping rings of U-shaped cross section. However, such clamping rings, which are usually made of thin metal sheets or of plastic, are not suitable for producing or for maintaining defined axial prestress between the individual rings of the axially split bearing ring and/or between the rolling elements of both rows as they roll on their raceways respectively.
In addition, the ball nut should be specially designed and machined for fitting or mounting the guide members such that the manufacturing procedures for the typical ball screw devices will be complicated and such that the manufacturing costs for the typical ball screw device will be greatly increased.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional motion guide apparatuses.